2 Lawson . — The Gametophytes, Archegonia, Fertilization , 
by Arnoldi, Shaw, and Strasburger, the only writers who have contributed 
to our knowledge of the gametophytes of this interesting Conifer. 
It is therefore the object of the present work to give a connected 
account of the events leading to the development of the gametophytes, 
sexual organs, fertilization, and embryo, thus completing as far as possible 
the life-history of Sequoia sempervirens. 
While the observations recorded by Shaw and Arnoldi are of great 
interest, they are by no means complete, and as we shall see later, some are 
even inaccurate. 
Shaw (1896) has given a description of how the male and female 
flowers develop in Sequoia sempervirens. When very young he finds that 
the macrosporangium is about as long as it is broad. The integument at 
this time consists of an epidermis and two layers of hypodermal cells. 
The integument develops rapidly and soon comes to be about twice as long 
as the nucellus. Soon after pollination the upper and inner layers of 
epidermal cells enlarge and by their elongation finally close the micropyle. 
By this means the pollen-grains are completely enclosed in a subconical 
cavity at the apex of the nucellus. Within the nucellus several sporogenous 
cells now make their appearance. Shaw reports that these cells divide 
twice, each one giving rise to four macrospores. Upon germination the 
macrospores develop a number of female prothallia. As the embryo-sacs 
increase in size they contain several nuclei. The further development of 
the prothallia was not observed. The archegonia were found to be very 
numerous and distributed over the upper portion of the prothallium and each 
one has but a single neck-cell. At the time of pollination each microspore 
consists of two cells, a large central cell with a large nucleus and a much 
smaller cell. As the pollen-tube develops the nucleus of the larger cell 
moves forward and enters the tube. The tube extends down between the 
nucellus and the integument and as often as not it branches. The further 
course of the tubes was not followed. Later a number of long suspensors 
bearing the young embryos on their tips were formed in the endosperm. 
Arnoldi (1900) has given a description of the manner of endosperm- 
formation in Sequoia sempervirens. According to this description the form 
of the embryo-sac may vary considerably. When young it consists of a 
very large central vacuole surrounded by a parietal layer of cytoplasm in 
which numerous nuclei are found. As the sac develops the parietal layer 
increases and the protoplasm accumulates in great abundance in the lower 
end and at the same time the free nuclei divide repeatedly. In the central 
region a portion of the vacuole remains, and here the cellular endosperm 
is formed by means of ‘ Alveolen 5 as Sokolowa describes for other Conifers, 
while the remaining endosperm is formed by ordinary free cell-formation. 
The development of the archegonia is confined to the tissue derived from 
the ‘Alveolen/ so that the prothallium has a distinct generative region. 
